leds-pwm.c

Go to the documentation of this file.

/*
 * linux/drivers/leds-pwm.c
 *
 * simple PWM based LED control
 *
 * Copyright 2009 Luotao Fu @ Pengutronix ([email protected])
 *
 * based on leds-gpio.c by Raphael Assenat <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/fb.h>
#include <linux/leds.h>
#include <linux/err.h>
#include <linux/pwm.h>
#include <linux/leds_pwm.h>
#include <linux/slab.h>

struct led_pwm_data {
    struct led_classdev cdev;
    struct pwm_device   *pwm;
    unsigned int        active_low;
    unsigned int        period;
};

static void led_pwm_set(struct led_classdev *led_cdev,
    enum led_brightness brightness)
{
    struct led_pwm_data *led_dat =
        container_of(led_cdev, struct led_pwm_data, cdev);
    unsigned int max = led_dat->cdev.max_brightness;
    unsigned int period =  led_dat->period;

    if (brightness == 0) {
        pwm_config(led_dat->pwm, 0, period);
        pwm_disable(led_dat->pwm);
    } else {
        pwm_config(led_dat->pwm, brightness * period / max, period);
        pwm_enable(led_dat->pwm);
    }
}

static int led_pwm_probe(struct platform_device *pdev)
{
    struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
    struct led_pwm *cur_led;
    struct led_pwm_data *leds_data, *led_dat;
    int i, ret = 0;

    if (!pdata)
        return -EBUSY;

    leds_data = devm_kzalloc(&pdev->dev,
            sizeof(struct led_pwm_data) * pdata->num_leds,
                GFP_KERNEL);
    if (!leds_data)
        return -ENOMEM;

    for (i = 0; i < pdata->num_leds; i++) {
        cur_led = &pdata->leds[i];
        led_dat = &leds_data[i];

        led_dat->pwm = pwm_request(cur_led->pwm_id,
                cur_led->name);
        if (IS_ERR(led_dat->pwm)) {
            ret = PTR_ERR(led_dat->pwm);
            dev_err(&pdev->dev, "unable to request PWM %d\n",
                    cur_led->pwm_id);
            goto err;
        }

        led_dat->cdev.name = cur_led->name;
        led_dat->cdev.default_trigger = cur_led->default_trigger;
        led_dat->active_low = cur_led->active_low;
        led_dat->period = cur_led->pwm_period_ns;
        led_dat->cdev.brightness_set = led_pwm_set;
        led_dat->cdev.brightness = LED_OFF;
        led_dat->cdev.max_brightness = cur_led->max_brightness;
        led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;

        ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
        if (ret < 0) {
            pwm_free(led_dat->pwm);
            goto err;
        }
    }

    platform_set_drvdata(pdev, leds_data);

    return 0;

err:
    if (i > 0) {
        for (i = i - 1; i >= 0; i--) {
            led_classdev_unregister(&leds_data[i].cdev);
            pwm_free(leds_data[i].pwm);
        }
    }

    return ret;
}

static int __devexit led_pwm_remove(struct platform_device *pdev)
{
    int i;
    struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
    struct led_pwm_data *leds_data;

    leds_data = platform_get_drvdata(pdev);

    for (i = 0; i < pdata->num_leds; i++) {
        led_classdev_unregister(&leds_data[i].cdev);
        pwm_free(leds_data[i].pwm);
    }

    return 0;
}

static struct platform_driver led_pwm_driver = {
    .probe      = led_pwm_probe,
    .remove     = __devexit_p(led_pwm_remove),
    .driver     = {
        .name   = "leds_pwm",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(led_pwm_driver);

MODULE_AUTHOR("Luotao Fu <[email protected]>");
MODULE_DESCRIPTION("PWM LED driver for PXA");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-pwm");